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Associated Press
Scientists are pushing for new ways to determine Alzheimer's disease, such as brain scans that find changes rather than relying on memory loss tests. They believe the earlier detection will improve studies and help find effective treatments.

Wednesday, April 11, 2018 1:00 am

Brain scans may soon determine dementia

Associated Press

Government and other scientists are proposing a new way to define Alzheimer's disease – basing it on biological signs, such as brain changes, rather than memory loss and other symptoms of dementia.

The move is aimed at improving research, by using more objective criteria like brain scans to pick patients for studies and enroll them sooner.

But it's too soon to use these scans and other tests in routine care, because they haven't been validated for that yet, experts stress. For now, doctors will still rely on the tools they've long used to evaluate thinking skills to diagnose most cases.

Regardless of what tests are used to make the diagnosis, the new definition will have a startling effect: Many more people will be considered to have Alzheimer's, because the biological signs can show up 15 to 20 years before symptoms do.

“The numbers will increase dramatically,” said Dr. Clifford Jack Jr., a Mayo Clinic brain imaging specialist. “There are a lot more cognitively normal people who have the pathology in the brain who will now be counted as having Alzheimer's disease.”

About 50 million people have dementia, and Alzheimer's is the most common form. In the U.S., about 5.7 million have Alzheimer's under its current definition, which is based on memory problems and other symptoms. About one-third of people over 70 who show no thinking problems actually have brain signs that suggest Alzheimer's, Jack said.

Dozens of hoped-for treatments have failed, and doctors think one reason may be that the studies enrolled patients after too much brain damage had occurred.

“By the time that you have the diagnosis of the disease, it's very late,” said Dr. Eliezer Masliah, neuroscience chief at the Institute on Aging.

“What we've realized is that you have to go earlier and earlier and earlier,” just as doctors found with treating cancer, he said.